Power tools, such as electric drills and electric screwdrivers, commonly include a motor, a transmission mechanism and an output shaft. The motor includes a drive shaft. The drive shaft is used to drive the transmission mechanism so as to output power to the output shaft.
When these tools are operated as hand held power tools, a user needs to grip the tool with one or two hands. If the hand held power tool has a large size, the tool is obviously not easy to operate. So, it is desired that hand held power tools not only satisfy the requirements of torque, speed and power, but also have a small size.
However, for currently known power tools, in order to obtain large output torque, the transmission mechanism commonly includes a multi-stage planet gear system and, in order to adjust the torque of the power tools, the transmission mechanism further includes an adjusting assembly. The known adjusting assemblies occupy a large space, which makes the power tools go against the miniaturization.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.